Comparative transcriptome analysis of Ziziphus jujuba infected by jujube witches' broom phytoplasmas

Ziziphus jujuba is one of the most important and widely grown fruits in China. Jujube witches' broom (JWB), an important disease in Z. jujube, could cause heavy loss for its industry. The disease is associated with the presence of 'Candidatus Phytoplasma ziziphi', a prokaryote, and very little knowledge is known about its interactions with jujube plants. Therefore, in the present study cDNA samples from healthy and diseased plants were sequenced on Illumina HISeq2000 and gene expression and metabolism regulation were compared. In the two libraries obtained from the leaves, 4266 differentially expressed genes (DEGs) were identified. Among them, 2070 genes were upregulated, and 2196 genes were downregulated. The comparison between the libraries from flowers showed 3800 DEGs, with 1965 upregulated and 1835 down-regulated genes. Among all these some specific genes were identified to be functionally related to the amino acid metabolism and the carotenoid pathway, which may be related to the lack of nutrition and the main symptoms of yellowing, brooming and small leaves. The results of this work provides a valuable resource for further studies of the disease on genetic and molecular levels.